When a remote center compliance type of device other than vertically oriented is required to carry large loads, there results a biasing of the device which causes misalignment between its operator means, e.g. tool, tool mating face, gripper, chuck, docking device, and the part with which it is to engage.
Remote center compliance (RCC) devices establish a center of compliance that is a point in space about which rotational motion and with respect to which translational motion may take place. The remote center may be within the RCC itself or its operator member, or parts held by the operator member, or external to it. A first type of RCC is disclosed in U.S. Pat. No. 4,098,001, Remote Center Compliance System, Paul C. Watson, July 4, 1978. A second type of RCC is disclosed in U.S. Pat. No. 4,155,169, Compliant Assembly System Device, Drake et al., May 22, 1979. Yet another type is disclosed in U.S. patent application Ser. No. 140,768, filed Apr. 16, 1980, Remote Center Compliance Device, Thomas L. De Fazio. All of the above disclosures are incorporated herein by reference. In the first type of RCC the location of the remote center is determined by the geometry of a plurality of radially disposed members whose focus is a point in space at which the remote center of compliance is located. In the second type of RCC device, the location of the remote center is determined by the geometry and stiffness of the radial members as well as by the mechanical stiffness of a deformable element which supports the radial members.
Attempts have been made to overcome this problem by using contructions which remove the weight of the tool or other apparatus from the RCC device. But oftentimes such a construction is not achievable and the problem persists.